The use of axial pin tumbular locks is well known and has been applied to numerous lock applications including those such as vending and dispensing machines. In many such applications the lock is required to provide more than one locking function. For example, it might be required that the lock provide key-pulls in more than one position. The application may dictate that in addition to the conventional 12 o'clock position, key-pulls be provided at say, 3 or 6 o'clock positions. Some other application may require only a momentary switch contact with key spring back. Conventional locks have attempted to provide such multiple operation capability but the resulting configurations have been complex. In addition, the shifting from one function to another has involved the disassembly of the complete lock mechanism and subsequent reassembly to obtain the new function. This makes the use of such locks extremely inconvenient, particularly in applications such as vending machines which are located on site and it is important that shifting of functions be accomplished without intricate manoeuvers.
The adaptation of mechanical key operated locks to incorporate electrical switch components typically has involved the use of a considerable number of individual parts stacked up on the rear end of the lock cylinder. Such arrangements present difficulties in the type of assembly operations that can be performed. Further, in such arrangements that combine the mechanical operation of the lock with electrical switching capability, the ability to disassemble the lock in order to either change keys or to change contact carrying elements has been either lost completely or provided only by means of specialty design.
One approach moving away from stack up arrangements of conventional switch locks is disclosed in U.S. Pat. No. 4,147,905 issued to Frank J. Scherbing. There, the pin tumbler sleeve and the electrical contact actuating elements are preassembled before insertion into the lock cylinder as a unit. This arrangement does reduce the number of parts as compared to a typical stacked up switch lock construction, but does not have the capability for providing optional features or different locking actions with the same switch actuating mechanism. A more recent approach, as disclosed in U.S. Pat. No. 4,394,551 issued to Frank J. Scherbing, discloses an electrical switch operating subassembly for a mechanical key actuated lock which is adaptable to commonly utilized lock sizes and may be disassembled for reaching or changing of switch contact elements. The essential components of this approach are two contact effecting interfitting members that are removably insertable in the lock cylinder and which coact with one another to make or break an electrical circuit on rotation of the lock operating spindle with the proper key. The switch operating subassembly also provides the rotational limits of the lock for switch "on" and switch "off" positions. Although this type of arrangement does provide adaptability to commonly utilized lock sizes and easy disassembly, it does not apply directly to a lock that has provision for multiple locking functions. Hence, there exists a need for a lock, specifically an axial pin tumbler lock, which has provision for multiple lock functions and is at the same time easily assembled and disassembled for rekeying or changing of switch contact elements or the like, and in addition, provides electrical switching capabilities.